Processors are comprised of individual circuits such as transistors, and each operation performed at a circuit typically requires at least a small amount of power. The operation of a circuit often generates a small amount of heat as a byproduct. While each individual circuit may use relatively little power and generate relatively little heat, current processors include millions—and often hundreds of millions—of densely packed circuits. The amount of heat generated by the processor further increases as the demands on the processor increase because more circuits are used more often. If the processor becomes too hot, the heat may damage the circuits.
A number of different systems and methods have been used to mitigate this problem. For example, some chips decrease the usage of their components (known as “throttling”) to prevent overheating. For example, a chip may decrease its clock speed so that the operations are performed more slowly, which gives the chip a little more time to cool down. The chip may also decrease the number of components it uses to perform operations. The chip may use other techniques as well, either alone or in combination with the foregoing techniques.
Typically, chips throttle when they reach a certain temperature, or at least assume that they reached or are approaching a particular temperature by monitoring their circuit usage. It is often preferable to prevent a chip from reaching the throttling stage because it indicates that the chip is working at less than peak efficiency.
Reducing the temperature of the chip's environment can help prevent overheating and throttling. For example, a computer may be placed in an air-conditioned location and a fan used to blow the cooler air across the processors in the computer. Other cooling methods are also available, such as liquid cooling.
Because not all processors are the same, it is helpful to know how much heat the processor will generate when designing a cooling system for the processor. Cooling systems can be expensive, which means that making a system cooler than necessary can result in unwarranted expense (e.g., faster fans often cost more than slower ones). On the other hand, if the system is not cool enough, the processor may get too hot and throttle.
Accordingly, to help system designers, processor manufactures will often define the “Total Dissipated Power” (TDP) of a processor. However, this information tends to define a distribution curve with a high variation across individual processors, which can prevent system designers from designing for the reasonable worst case. For example, if the TDP indicates an average power consumption of 80 watts and the cooling system is perfectly designed for the average, then many of the processors will underperform.
Some systems and methods measure the power consumed by processors when running programs. However, such systems unsatisfactorily address issues associated with the thermal aspects of the processor and, thus, can be unpredictable. For example, some systems and methods measure the consumed power in a way that changes depending on the temperature of the surrounding environment, thus requiring replication of the external environment in order to provide results that can be meaningfully compared with other processors.